Feed guide for sheet material

ABSTRACT

Apparatus such as a sewing machine, having means, e.g., a feed dog cooperating with a presser foot, to pass sheet material over a work surface through a work point, is improved by adapting it to automatically steer or guide the sheet material through the machine. A rotatable gripping means such as a contact ring about the work point is arranged to intermittently engage the sheet material, synchronously with the action occurring at the work point. Associated therewith is means for actuating the gripping means into contact with the sheet material and for imparting a controlled rotational movement to the gripping means so that it moves arcuately with respect to the work point thus exerting a guiding action on the sheet material. The gripping means can be located above or below the sheet material and can have opposed to it a cooperating surface to assist it in its clamping and guiding action. The rotational motion of the gripping means can be controlled by means of an optical edge sensor or it can be preprogrammed as by computer techniques. The fact that the rotatable gripping means contacts the sheet material at least over a series of points, preferably over an area at least in part surrounding the work point, and the fact that the position of the gripping means in contact with the sheet material moves relative to the work point in the plane of the sheet material while it is exerting its guiding action, are considered distinguishing characteristics of the invention.

United States Patent Rovin J M 17 1 r [73] Assignee: Ivanhoe ResearchCorporation, New York,

[22] Filed: July 23, 1969 [21] Appl.No.: 854,333

Related U.S. Application Data [63] Continuation-impart of Ser. No.659,096, Aug. 8,

1967, abandoned.

[52] U.S.Cl ..ll2/l21.11, 1 12/153, 112/204, 271/53 [51] Int. Cl ..D05b19/00, D05b 27/14 [58] FieldoiSearch ..l12/121.ll,l21.12,l2l.15,

[56] References Cited UNITED STATES PATENTS 519,676 5/1894 Jones..112/102 R X 874,032 l2/1907 Pfeufen. ..112/204 R X 1,808,805 6/1931Bihler. ..112/l2l.24 2,261,644 11/1941 Cockrell .l12/121.12RX 2,971,4832/1961 Cordier ..112/205 3,072,081 l/1963 Milligan et al.. "112/121 123,080,836 3/1963 Clemens et al. l12/121.11 3,139,051 6/1964 Story..112/204 3,170,423 2/1965 l-lenebry ..112/121.l2 3,182,616 5/1965Cremer ..112/l21.12 3,384,755 5/1968 Williamson et al. ..250/2272,074,488 3/1937 Prazak ..l l2/l21.24 3,354,319 11/1967 Loewen et a1...250/227 3,385,245 5/1968 Ramsey et al ..112/12l.l2 3,434,439 3/1969Winberg l2 /l2l.l2

3,459,145 8/1969 Ramseyetal ..1l2/12l.11

FOREIGN PATENTS OR APPLICATIONS 13,073 4/1903 Austria ..1 12/204 572,446H1958 Italy ..112/204 Primary Examiner.lames R. Boler Attorney-Burgess,Dinklage & Sprung [57] ABSTRACT Apparatus such as a sewing machine,having means, e.g., a feed dog cooperating with a presser foot, to passsheet materi- 211 over a work surface through a work point, is improvedby adapting it to automatically steer or guide the sheet materialthrough the machine. A rotatable gripping means such as a contact ringabout the work point is arranged to intermittently engage the sheetmaterial, synchronously with the action occurring at the work point.Associated therewith is means for actuating the gripping means intocontact with the sheet material and for imparting a controlledrotational movement to the gripping means so that it moves arcuatelywith respect to the work point thus exerting a guiding action on thesheet material.

The gripping means can be located above or below the sheet .material andcan have opposed to it a cooperating surface to assist it in itsclamping and guiding action. The rotational motion of the gripping meanscan be controlled by means of an optical edge sensor or it can bepreprogrammed as by computer techniques.

The fact that the rotatable gripping means contacts the sheet materialat least over a series of points, preferably over an area at least inpart surrounding the work point, and the fact that the position of thegripping means in contact with the sheet material moves relative to thework point in the plane of the sheet material while it is exerting itsguiding action, are considered distinguishin characteristics of theinvention.

34 aims 1 2 Drawing Figures PATENTEUHARZ] I972 SHEET 1 BF 8 INVENTOR BY.s ilk/24 a ATTORNEY HERMAN ROVIN PAIENTEUIARZI I972 3.650.229

SHEET 2 UF 8 INVENTOR HERMAN ROVI N PATENTEDMARZI 1972 3.650.229

sum 3 OF 8 HERMAN ROVIN PAIENTED MR2] I972 SHEET 4 [IF 8 INVENTCR vHERMAN ROVIN mmaim mozmmmuwm mmdim JOFPZOQ k ww PATENTEDHARZI I9723,650,229

sum 5 [1F 8 INVENTQR. HE RMAIV R0 VIN BY W WW Q Q PATENTEDMARZ] I972 3.6 50,22 9

SHEET 6 [1F 8 .FIG.8

INVENTOR. HERMAN ROI/IN MW WM PMENTEUMARZI m2 SHEET 7 [IF 8 FIG. IO

INVENTOR. HERMAN ROW/V VAIENTEDMAR 21 I872 FIG. ll

FIG. I2

lllVh/IOP HERMAN HOV/N FEED GUIDE FOR SHEET MATERIAL RELATED APPLICATIONThis application is a continuation-in-part of application Ser. Number659,096, tiled Aug. 8, I967, now abandoned, and entitled Feed Guide forSheet Material.

This invention relates to a feed guide for sheet material. The inventionmore particularly relates to an arrangement for controlling the courseof sheet material being fed over a work surface past a work point, asfor example, over the throat plate of a sewing machine beneath theneedle thereof.

The invention furthermore relates to an optical edge sensing arrangementto control actuation of the guide or which can be used in connectionwith other guiding arrangements.

In many devices, sheet material is automatically fed over a work surfacepast a work point such as in the manufacture of leather goods, clothingand sails. While the feed is automatic, the course of the material mustusually be manually varied or controlled as, for example, to follow theedge of the material, a pattern line, or the like. For instance, whencloth or leather is fed through a sewing machine, while the feed iseffected automatically by the sewing machine feed dogs, an operator mustguide the material in order to maintain the desired stitch line, or tofollow the contour of the material edge. The same type of manualguidance is required in various other operations such as in certainperforation operations on sheet material. skiving operations on leatherand the like.

This invention is directed to this and other problems, and proposes animproved apparatus with means for controlling the course of a sheetmaterial being fed over a work surface past a work point, moreparticularly a guiding device which will automatically guide sheetmaterial through a sewing machine.

THE DRAWINGS FIG. I is a perspective view of a sewing machine providedwith an embodiment of the guiding arrangement and sensor in accordancewith the invention;

FIG. 2 is a partial exploded perspective view of the guiding arrangementofthe device shown in FIG. 1;

FIG. 3 is a perspective view partially in section showing a portionofthe device shown in FIG. 1;

FIG. 4 is a cross section through the presser disk of the guiding deviceshown in FIG. 1 showing one position of operation;

FIG. 5 is a cross section through the presser disk of the guiding deviceshown in FIG. 1 in another position of operation;

FIG. 6 is a circuit and block diagram illustrating the edge sensing andguide control device shown in FIG. 1;

FIG. 7 is a broken-away perspective view of another embodiment of thisinvention;

FIG. 8 is an exploded perspective view of the rotatable gripping meansshown in FIG. 7;

FIG. 9 is a cross section of the floating ring 75 taken along thesection line shown in FIG. 8;

FIG. 10 is a perspective view of a further embodiment wherein therotatable gripping means of this invention is located below rather thanabove the sheet material;

FIG. 11 is a plan view of the clamping element 113 shown in FIG. 10which assist the action of the gripping means; and

FIG. 12 is a cross-sectional view of element 113 and of the presserplate of the machine shown in FIG. 10.

DESCRIPTION The device in one embodiment of this invention for guidingsheet material being fed over a work surface past a work point has apresser plate positioned opposed to the work surface for the passage ofthe sheet material between it and the work surface and is preferablybiased to press the sheet material in sliding contact with it and thework surface. Gripping means are connected to the presser plate and aremounted for at least limited rotary motion about an axis substantiallyextending through the work point. The gripping means are selectivelyadapted for holding engagement with the sheet material during rotarymovement thereof without substantially impeding the feed of thematerial. Means are provided imparting rotary movement to the grippingmeans to vary the course of the sheet material being fed. Preferably thegripping means is in the form of a friction surface at the peripheraledge of the presser plate as for example, in the form of an annularfriction ring rotatably mounted about the plates periphery which allowsthe gripping action by differential friction, i.e., when effecting thegripping action exerts a greater friction force on the sheet materialthan does the work surface or presser plate.

The presser plate is preferably mounted for limited axial movementtoward and away from the work surface and is preferably intermittentlymoved toward and away from the work surface so as to effect the grippingaction when moved toward the work surface and to allow the feed to occurintermittently when moved away from the work surface.

An edge sensor is preferably provided for controlling the rotarymovement imparted to the gripping means. The edge sensor is preferablyan optical edge sensor having a photosensitive cell for receivingreflected light signals from a narrow area along the path of travel ofthe edge of material through the machine and effects rotation of thegripping means in one direction when the intensity of the reflectedlight signals exceeds a predetermined value and in the oppositedirection when the intensity of the reflected light signal is below thisvalue.

In accordance with an embodiment of the invention a fiber optic cable isprovided which terminates directly at the area in question. A portion ofthe optic fibers of this cable are connected to the photosensitive celland a further portion are connected to a light source for illuminatingthe area. The photosensitive cell is preferably so arranged that whenthe edge of the material bisects the illuminated area in question thesignal produced is at its null or neutral point. The illuminated area inquestion is preferably beneath the presser disk and the presser disk ismost preferably provided with a contrast plate, i.e., a plate having acontrasting reflectivity with respect to the sheet material, which isresiliently urged under the edge of the material.

Referring to the embodiment shown in the drawings, 1 represents aconventional sewing machine of the lock stitch type provided with areciprocating needle 2, and a throat plate 3 (FIG. 3) over which thematerial to be sewn is passed and which is provided with an opening intowhich the needle extends on its stitching stroke. Below the throat platea conventional bobbin (not shown) is provided as are the conventionalfeed dogs 4 (FIG. 3).

In accordance with the invention the conventional presser foot of thesewing machine is replaced with a presser plate in the form of the disk5 which is attached to the end of the presser foot shaft 53 which may beraised and lowered in the conventional manner and when lowered in itsoperational position as shown, resiliently presses the disk 5 againstthe throat plate while allowing limited axial movement of the disk 5away from the throat plate against a spring force in the same manner asconventionally occurs in connection with the presser foot. An opening 6extends through the presser disk 5 through which the needle 2 may extendor be retracted. Rotatably mounted about the periphery of the presserdisk 5 is the ring bushing 7. Secured to the periphery of this ringbushing is the ring gear 8 and secured to the lower surface of the ringbushing 7 is the annular rubber friction ring 9. The bushing 7 with itsconnected parts 8 and 9 is held against axial movement, while allowingrotary motion by means of the upper flange 10 on the disk 5 and thelower plate 11, the bottom surface of which constitutes the lowersurface of the disk. This lower surface is preferably of a materialhaving a low coefficient friction and may for example, be formed of thesame material as the throat plate, as for example polished metal havinga mirror finish, chrome plated, or the like. This surface may also be ofa low coefficient friction plastic or coated with a nonstick plastic, orthe like. The surface in any event has a substantially lower coefficientof friction with the material to be passed through the machine than doesthe friction ring 9, so that there is greater friction between thematerial and the friction ring 9 than there is between the material andthe throat plate and the material and the opposed surface of the presserdisk. Movement of the friction ring 9 will thus cause the material tomove in fixed contact therewith while sliding in contact with the throatplate 3 and lower surface 11 of the presser disk, by differentialfriction. Mated in engagement with the ring gear 8 is the drive gear 12.The ring gear 8 may slide a limited degree in its axial direction whilebeing maintained meshed with the drive gear 12 as may be noted I fromFIGS. 4 and 5. The drive gear 12 is mounted at the end of the idlershaft 13 which rotates in the bearings 14 and 15, mounted between theplates 16 and 17 which in turn are mounted in spaced relationship on theend of the AC servo motor 18. The motor 18 has a drive shaft 19 providedwith a gear 20 which is meshed with the gear 21 seated on the idlershaft 13 so that rotary motion of the servo motor and its drive shaft 19will be transmitted to the ring gear 18 through the gear train 20, 21,12. The presser disk is connected to the presser post or bar 53 by meansof the bushing arrangement 22. The presser disk 5 is provided with aslotted opening 23 in which is guided the finger bar 24 on the pin 25,which is springloaded by the spring 26. Connected to the lower end ofthe finger bar 24 is the contrast plate 27. This plate is so positionedthat it will be resiliently forced under the edge of the sheet materialbeing passed through the needle of the machine as hereinafter described.A further opening 28 extends at an angle through the presser disk 5 infront of the opening 6 in the normal direction of feed of materialthrough the machine. Extending in this opening 28 is the end 29 of thefiber optic cable 30. The opposite end of the fiber optic cable 30extends into the control box 31 which contains the photo sensor andelectrical elements as shown in FIG. 6. In the control box 31 the fibersof the fiber optic cable 30 is split into two branches 32 and 33, eitherfor example, randomly with about half of the fibers extending on eachbranch, or with, for example, the central fibers extending in branch 32and the peripheral fibers extending in the branch 33.

The light from the incandescent bulb 34 is transmitted through the opticfibers of the branch 33 through the cable 30 and is projected from theend 29 as an illuminated spot 35 in the normal path of travel of theedge of the material 36 through the machine. The light is reflected backfrom this illuminated spot and picked up by the other optic fibers inthe cable and is transmitted through the fibers of the branch 32 intothe photosensitive cell 37 which is in the form of a conventionalphotoresistor, the resistance value of which varies inversely with theintensity of light striking the same. The photoresistor 37 forms a partof a circuit fed with direct current from the cell 38. Current from thecell 38 flowing through the central line 39 of the circuit is tapped offthrough the potentiometer 40 and flows through the photoresistor 37 tothe base of the transistor 41. A further portion of the current from thecell 38 flows through the branch 42 of the circuit through the fixedresistor 43 and the collector and emitter of the transistor 41 toground. The photoresistor 37 controls the base current of the transistor41 and thus controls the collector-emitter current of the transistor sothat the current flowing through the line 42 and the voltage drop acrossthe resistor 43 will be directly controlled and amplified by changes inthe resistance of the photoresistor 37. As an increasing amount of lightstrikes the photoresistor its resistance decreases and the voltage dropacross the resistor 43 increases. In the same manner, as theintensity oflight striking the photoresistor 37 decreases, its resistanceincreasescausing a decrease in current fiow through the line 42 and a decrease inthe voltage drop across the resistor 43. The voltage between theresistor 43 and transistor 41 is fed by line 44 into the amplifier 45 asan input signal voltage. The value of this voltage will, of course,decrease as the intensity of light striking the photoresistor 37increases.

The potentiometer 40 may be used as a scale control to adjust theresponse of the photoresistor 37 to produce a desired average outputvoltage between maximum and minimum light values striking thephotoresistor 37 under given conditions and to prevent overloading ofthe transistor 41. A further line 46 is connected to the cell 38 andprovided with the variable resistance 47 which is' connected to theamplifier 45 as a reference input signal through the line 48. Theamplifier 45 is a conventional differential amplifier which amplifies asa DC output signal the difference between the voltages of the lines 44and 48. The value of the reference voltage may be adjusted by varyingthe resistance 47 through an external control knob as shown in FIG. 1.The gain of the amplifier 45 may be controlled by the gain control 49.The amplified DC signal from the amplifier 45 is passed into the chopper46 which converts thissignal to a square wave 60 cycle AC signal. The ACsignal from the chopper 46 is then fed through the booster amplifier 47where the same is amplified to a value suitable for the control phase ofthe servo motor 18 to which it is fed. A tuned capacitor 50 is providedfor impedance matching. The servo motor 18 is a conventional two-phaseAC servo motor which is provided in addition to the control phase with a60 cycle reference or drive phase. The motor will rotate in onedirection when the control phase is out of phase with the drive phase,and in the opposite direction when 270 out of phase with the drivephase. If a positive signal is fed by the amplifier 45 into the chopper46, the amplified control phase will be 90 out of phase with the drivephase causing rotation in one direction. If on the other hand, theamplified DC signal fed into the chopper 46 is a negative signal, theamplified AC signal from the amplifier 47 will be 270 out of phase fromthe drive phase causing rotation in the opposite direction.

In order to prevent excess control oscillation a tachometer damper 51may be provided in order to create a viscous drag. The tachometer 51 maysimply be constructed so as to provide a signal dependent on the speedor rotation of the servo motor 18, which signal opposes the signal ofthe amplifier 45 and cancels a portion thereof.

in operation the presser disk 5 is raised by raising the post 53 in theconventional manner, as for example, by means of the control handle 52.The material to be sewn is placed in the machine in the conventionalmanner. Assuming that a stitch line is to be sewn following the edge ofthe material as shown in FIG. 1, the material is positioned beneath theneedle of the machine in its proper starting position and the disk 5lowered into its operational position so as to holdthe material betweenit and the throat plate. The disk 5 and the end 29 of the fiber opticcable 30 is adjusted so that the spot of light 35 projected from thecable is bisected by the edge of the material. If there is not asubstantial difference in the reflectivity between the material beingsewn and the area past the edge, as for example when two pieces ofmaterial are being sewn together, a contrast plate 27 being ofsubstantially different reflectivity than the material may be used andmay be inserted under the edge being sewn as shown in FIG. 6. Theinsertion of the contrast plate 27 so that the same extends under theedge, may be facilitated by manipulation of the finger lever 24. Withthe material in this position the potentiometer 40 is adjusted so thatthe output voltage for the line 44 into the amplifier 45 is at thedesired value. This value may be ascertained, for example, by means ofthe voltage meter 54. The reference voltage fed into the amplifier 45 isthen adjusted by means of the variable resistance 47 to equal this inputsignal voltage so that this constitutes the null or zero point and thereis no output signal from the amplifier 45 and the servo motor 18 will beat rest. The sewing machine is then started and operated in itsconventional manner and begins to stitch the material. Assuming that thematerial reflects less light than the contrast plate 27, and thematerial begins to move out of the desired path of travel so that forexample, the edge 36 would move in a direction moving the stitch linetoo far from the edge, a greater area of the light spot 35 will becovered by the material cutting down the amount of light reflected andthus the light signal passing through the branch 32 to the cell 37. Thiswill increase the resistance of the cell 37 decreasing the base currenton the transistor 41 and thus decreasing the amount of current which thetransistor will pass from the collector to the emitter and the amount ofcurrent passing through the line 42 to ground. This will decrease thevoltage drop across the resistance 43 and thus will increase the voltagesignal fed through the line 44 into the amplifier 45 so that this signalvoltage is greater than the reference voltage fed in at 48 on thepositive side. The amplifier 45 will amplify this positive DC signalwhich is converted by the chopper 46 to an AC signal 90 out of phasewith the reference or drive phase fed to the servo motor 18. This ACsignal will then be amplified by the amplifier 47 and fed as the controlphase to the servo motor 18 causing rotation in a counterclockwisedirection which through the gear train 20, 21 and 12 will cause rotationof the ring gear 7 in a clockwise direction rotating the friction ring 9therewith.

As the needle 2 of the sewing machine retracts as shown in FIG. 4, thefeed dog 4 raises and begins its transport or feed stroke. This raisingof the feed dog forces the presser disk 5 to raise, as shown in FIG. 5,raising the friction ring 9 from contact with the sheet material. Thesheet material may thus be transported in the conventional manner by thefeed dog 4 in sliding contact with the throat plate and presser plate.When the feed dog 4 reaches the end of its transport or feed stroke asshown in FIG. 3, it lowers, as shown in FIG. 5, so that the presser disk5 is forced downward by the springloaded presser foot post 53 and thefriction ring 9 is pressed in friction contact with the material. Atthis point as shown in FIG. 5, the sewing machine needle has begun itsstitching stroke and begins to pierce the material. Rotation of thefriction ring 9 will thus cause the material by differential friction toslide in contact with the throat plate and pivot about the needle 2,steering and guiding the material so as to direct the stitching towardthe edge. This change in the course of feed by rotating the materialabout the needle duplicates manual manipulation and guiding. The rotaryguiding motion will continue throughout the stitching stroke and willonly be interrupted when the feed dog again begins its feed or transportstroke and again raises the presser disk 5 so that the friction ring isout of contact with the material.

The actuation of the servo motor 18 so as to rotate the ring 8 andfriction ring 9 in a clockwise direction will continue until the edge ofthe material again bisects the light spot 35 so that the amount ofreflected light striking the photoresistor 37 is just sufficient so thatthe voltage in the line 44 again equals the reference voltage from theline 48 at which point there will no longer be an output signal from theamplifier 45 and the servo motor will not be actuated.

If the edge of the material moves out of line in the opposite directionso that the stitch line is too close to the edge, the amount ofreflected light will increase causing a decrease in the resistance ofthe element 37, and increase in the collector emitter transistor currentof the transistor 41, and an increase in the current flowing through theline 42, with an increase voltage drop over the resistance 43 and thus adecrease in the signal voltage passing through the line 44. With thisdecrease in signal voltage, the input of the reference voltage throughthe line 48 will exceed the signal voltage thus causing the amplifier 45to produce a negative voltage which is converted by the chopper 46 to anAC signal 270 out of phase with the drive voltage of the servo motor 18.This AC signal amplified by the amplifier 47 is fed as the control phaseto the servo motor 18 causing rotation in the opposite direction whichin turn rotates the friction disk 9 counterclockwise directing thestitch line away from the edge.

Not only is the direction of rotation of the servo motor 18 controlledin dependence on the signal voltage exceeding or falling below thereference voltage fed to the amplifier 45, but the amplitude of thecontrol phase signal varies with the magnitude of this difference sothat the speed of the servo motor will increase in proportion to thevariation of the reflected signal from its zero or null value. Thus,when the entire edge of the material covers the light spot 35, thedifference will be at a maximum and the motor speed at its greatest. Inthe same manner when the entire edge is out of the light spot, thedifference will be at a maximum on the other side of the null or zerovalue and the motor speed at a maximum in the opposite direction.

The tachometer damper 51 will tend to slow the motor down after it hasreached its maximum speed and when it is thus again moving the materialso that it is approaching the desired position and will tend to preventovershooting and oscillations.

The edge follower in accordance with the invention will not only followan actual edge, but will follow any line having a boundary of differentreflectivity thereacross and as used herein and in the claims, an edgeis intended to designate not only a physical edge, but such a visualedge.

In place of the photo resistor 37, any photosensitive element may beused and any control circuit drive combination in which the direction ofdrive is reversed when the sensed reflective light value exceeds orfalls below a predetermined value. Thus, a simple photosensitive cellmay be used to receive the reflected light from the area of the edge andthe light generated electrical signal may be used to control the motoror drive so that the drive is reversed as the signal exceeds or fallsbelow a predetermined value, the value being determined by the signalproduced when the edge is in its desired position.

In place of an AC servo motor any known or conventional reversible drivemay be used or the drive may be magnetically or hydraulically reversed,the reversal controlled by the signal as described. The edge sensor maybe used for controlling the drive of any known or conventional guidingarrangement.

In the same manner, the guiding arrangement in accordance with theinvention need not be controlled by the edge sensor as described, butmay be controlled in any other desired manner. Thus for example, thesame may be used in connection with any known or conventional edgesensor or control device. For example, the servo motor may be driven bya programming device so that the machine will follow prearrangedprogrammed patterns. The program signals may be on magnetic tape, punchtape, or the like. The device may also be programmed in conjunction witha stitch counter so as to follow a course or pattern dependent on thenumber of stitches so that, for example, increments of rotation areimparted to the servo motor 18 in sequence after predetermined numbersof stitches have been sewn by the machine.

The device may also be controlled mechanically, as for example, througha cam actuated drive which rotates the ring gear 8, or mechanicallyguided by a mechanical follower, as for example, which follows the edgeand mechanically, hydraulically or electrically causes rotation of thering gear 8 in accordance with variations of its position.

If the device is to be used with a walking needle type sewing machine,i.e., a sewing machine in which the feed dogs move on their feed strokeat the same time that the needle pierces the material on its sewingstroke with the needle and generally the presser foot moving or walkingalong with the feed dogs, then a sufficiently large opening or slotshould be provided in the presser plate to allow for this walkingmovement of the needle. When the presser foot of the machine also movesor walks, the presser disk cannot be attached to the presser foot shaft,but should be secured to the machine so that it will not be imparted anylinear motion and will only be provided the rotary motion required. Mostpreferably with this form of machine the presser plate is in the form ofan annular ring surrounding the walking needle and presser foot of thesewing machine. This annular presser plate is reciprocated up and downby a mechanical connection to the sewing machine drive effecting itsdown stroke in gripping engagement when the needle of the machine isretracted, and effecting its up-release stroke when the needle of themachine penetrates the fabric, and is maintained in this releasedposition until the needle and feed dogs complete their walking motion.

While the device has been shown in combination with a sewing machine,the same may be used in connection with any other device in connectionwith which sheet material is fed over a work surface past a work pointand in connection with which the material should be guided through thework point. Thus, the device may be used in connection with skivingmachines for leather, engraving machines, marking machines, perforatingmachines, riveting machines, cutting devices, nibblers for leather orsheet metal, embossing machines, or the like.

In place of the friction ring 9, any other gripping device may be used,as for example, pins, dogs, or the like, which may be actuated insynchronization with the feed so as to intermittently move or retractout of gripping engagement on the feed stroke. When used in conjunctionwith a continuous feed machine, the gripping means should be such as toprovide sufficient grip on the material to impart rotary motion thereof,without interfering with the feeding action. Thus, the gripping meansmay be in the form of a friction ring which provides sufficient frictionbetween it and the material to rotate the material while allowingsliding actuation in the feed direction.

When two overlapping pieces of sheet material are being fed, care shouldbe taken that the gripping device will not solely grip the top piece andmove the same relative to the lower piece. If this is likely to occurand it is not possible to at least temporarily secure the two sheetstogether, a gripping arrangement may be provided which willsimultaneously grip both sheets. Thus, in connection with fabric andother sheet material which is easily perforated the gripping means maybe in the form of pins which will penetrate the upper sheet intogripping engagement with the lower sheet.

FIGS. 7, 8 and 9 illustrate four additional embodiments of thisinvention, namely: (1) the rotatable gripping means is mounted from thehead of sewing machine independently of the presser foot, (2) a floatingring is placed in the throat plate opposed to the annular gripping meansto assist the rotational movement of the material being processed overthe throat plate, (3) the contrast plate is adapted for right or leftpositioning, and (4) fluid actuated-lifting means associated with thethroat plate are present to assist lifting of the material off thethroat plate and the insertion thereunder of the contrast plate.

Referring to FIGS. 7, 8 and 9, a support bracket 70 is mounted to thehead of a sewing machine (not shown). Through it extends thereciprocating needle shaft 71 and the presser foot shaft 72, both ofwhich are conventional. Opposed to the presser foot and needle is thefeed dog arrangement 73, also conventional, supported of course in asuitable throat plate 74. The throat plate contains a floating ring 75that is free to rotate about the axis of the needle and has a diameterand width about equal to that of the revolving gripping means ormanipulator 80, explained infra.

The optical edge sensor 77 and contrast plate 78 are supported from thesupport bracket 70 by means of a vertically adjustable guide 76. Theupper end of guide 76 is attached to a rotatable ring 79 within bracket70, that has suitable stops (not shown) so that it can be rotated 180from the right position, illustrated, to a reverse or left position.

The manipulator or rotatable gripping means is generally indicated at80. A shaft 81 supports it from thehead of the machine, and can raise orlower manipulator 80, as previously described. The manipulator consistsof a stationary pivot plate 82 affixedto the end of shaft 81, a bearingring 83, a securing ring 84, a gear 85, a stiffener ring 86, amanipulator guide segment 87, and the manipulator ring proper 88, all ofwhich are held together by fastening means 89 and 90. The manipulator isdriven or controlled by gear 91 which attaches to the servomechanism,previously explained, through shaft 92.

It can be seen that the manipulator ring 88 consists of a lower workingring 8812 supported by a strut which permits ring 85-gear 91, etc. to bepositioned somewhat up and out of the way. Preferably the lower surfaceof the working ring 88b provides a high friction area, with respect tothe material being guided.

Since the manipulator is not connected to the presser foot it canoperate independently of the presser foot, as might be desired with awalking needle machine, or the presser foot as such can be done awaywith entirely.

In operation, the manipulator 80 will usually descend and grip thefabric in conjunction with floating ring 75, and exert its fabricguiding action during periods the needle is in the up position, free ofthe fabric. Because the manipulator exerts its gripping action over anarea, in this case a full 360, it is independent of any need to have thefabric restrained at a pivot point, such as about a needle penetratingthe fabric as was the case with some earlier prior art machines.

Floating ring 75 is used to assist the fabric's swiveling over thethroat plate. It may in some cases be slightly raised above the level ofthe throat plate.

Items 97 and 98 in FIG. 7 are simply hydraulic lifters that can beactuated when desired to lift the edge of the fabric being processed sothat the contrast plate 78 can be inserted thereunder. A lifter rod 99extending through a suitable clearance hole 100 is illustrated.

FIGS. 10, 11 and 12 illustrate another embodiment of the inventionwherein the manipulator is inverted and associated with the throatplate, which means that a lesser number of operating pieces have to beassociated with the head and the work area is less obstructed.

The head of the sewing machine is generally indicated at l 10 anddependent from it is the needle shaft, 111 and the optical edge sensor 112, which need not be further explained.

Since the manipulator ring, 1 15 is in the throat plate 116, it isdesirable to have a rotatable floating ring positioned on the upper sideof the fabric being worked on to urge the fabric against the manipulatorduring the periods it is to exert its guiding action. To this end, afloating ring 113, about the presser foot 112, is positioned from thehead of the machine by means of a reciprocating shaft 114, the drivingmechanism for which while illustrated, need not be explained. Thefloating ring is loosely rotatably mounted on a bracket 118 which inturn is clamped to shaft 114. The under side of floating ring 113 canhave a resilient material 113a affixed thereto, such as a sponge foraccommodating variation in thickness of material, although this is notnecessary. The floating ring 113-113a serves to urge the material intopressing engagement with the manipulator ring 115. Preferably the uppersurface of the manipulator ring 115 provides a high friction area, withrespect to the material being guided.

Since the periodic gripping action effected between the floating ring113 and manipulator 115 for guiding the material results from thedownward pressing action of the reciprocating floating ring 113, it isnot necessary for the manipulator 115 to reciprocate as in the earlierembodiments. A gear ring 119, suitably and simply mounted in throat 116and attached to the manipulator ring 115, can be driven by a drive gear120 associated with the servomechanism or control means.

With particular reference to FIGS. 11 and 12, the floating ring 113 isshown in greater detail. The bracket 118 supports three supportinggrooved nylon bearings which hold in their grooves ring 113 for freerotation. Presser foot 112 is located below and free of ring 113, withits supporting shaft 126 extending through the opening in bracket 118.As in the embodiment shown in FIG. 7, with some types of sewing machinedesigns, presser foot 1 12 can be eliminated.

It can be appreciated that instead of using an edge sensor to controlthe course of the fabric through the machine, the servo mechanism orcontroller can just as well be programmed to direct the fabric along apredetermined path. For example, in the manufacture of sails theapparatus of this invention can be used to mark out on the sailcloth apredetermined pattern. A programmed computer can be used to control theaction of the manipulator to scribe or mark the complicated contours ofeach piece of the sail on a bolt of sailcloth rather than using theconventional method of lofting the design by hand.

Thus, with reference to FIG. 7, a servo mechanism 218, similar to item18 of FIG. 1, can be used to drive shaft 92.

Servo 218 can be a DC mechanism, which usually is more sensitive, andchopper 46 of FIG. 6 can therefore by eliminated. The servo mechanismcan be controlled by a computer-controller 200 that is programmed as bypunched tape or magnetic tape to cause the manipulator 80 to undergo apredetermined series of movements in conjunction with or independentlyof the use of an edge sensor. Controller 200 could also embody theequivalent of a stitch-counter so that after a predetermined number ofstitches had been made, the manipulator 80 would alter the course of thematerial through the machine.

lt will be appreciated that the particular edge sensor described inconjunction with FIG. 1 can be replaced with other sensing means. Forexample, a photoelectric cell can be placed on one side of the materialand a light source on the other, and the fiber optic bundle and thereflectance plate can be done away with. The position of the edge of thematerial would then directly affect the amount of light falling on thephotoelectric cell.

Having described this invention, what is sought to be protected byLetters Patent is succinctly set forth in the following claims.

lclaim:

1. In combination with a sewing machine having a throat plate, areciprocating needle and a synchronized feed dog; a presser platemounted opposed said throat plate for the passing of material to be sewnbetween it and said throat plate, gripping means connected to saidpresser plate and mounted for at least limited rotary motion aboutsubstantially the axis of said needle, means for intermittentlyactuating said gripping means in holding contact with material beingpassed between said presser and throat plate in synchronization withstitching action of said needle, and means for imparting rotary movementto said gripping means to vary the course of material being passedthrough the sewing machine.

2. Combination according to claim 1 in which said gripping meanscomprises a friction surface at a peripheral portion of said presserplate, allowing gripping action by differential friction, said presserplate being mounted for limited axial movement toward and away from saidthroat plate, and in which said means for intermittently actuating saidgripping means is means for axially moving said presser plate.

3. Combination according to claim 2 in which said presser plate isresiliently biased against said throat plate for the gripping ofmaterial passed through the machine by said friction surface and ismounted to be axially forced away from said throat plate by said feeddog upon its intermittent feed actuation, whereby the gripping action ofsaid friction surface is released.

4. Combination according to claim 3 in which said presser plate is inthe form of a disk having an annular friction ring rotatably mountedabout its periphery and extending past the plane on its surface, saidfriction ring comprising said gripping means.

5. Combination according to claim 4 in which said means for impartingrotary movement to said gripping means comprises a servo motor.

6. Combination according to claim 5 in which said friction rings iscoaxially connected to a ring gear driven by said servo motor.

7. Combination according to claim 6 including edge sensing meanscontrolling said servo motor.

8. Combination according to claim 7 in which said edge sensing meanscomprises an optical edge sensor having photosensitive means forreceiving reflected light signals from a narrow area along the path ofmaterial travel through the machine, and means for actuating said servomotor for rotation in one direction when the intensity of the reflectedlight signal received by said photosensitive means exceeds apredetermined value and in the opposite direction when the intensity ofthe received reflected light signal is below said value.

9. Combination according to claim 8 in which said photosensitive meansis connected for receiving reflected light signals from a narrow areaadjacent the sewing machine needle and includes means for illuminatingsaid area.

10. Combination according to claim 9, including a fiber optic cableterminating adjacent said area, a portion of the fibers of said cableleading to said photosensitive means, a further portion leading to alight source for illuminating said area.

1 1. Combination according to claim 10 including a contrast plateconnected to said presser plate and positioned to extend under the edgeof material passing through said area.

12. Combination according to claim 11 in which said area immediatelyprecedes the sewing machine needle along a path of travel of materialthrough the machine.

13. Combination according to claim 12 in which said friction ring is arubber ring allowing gripping action by differential friction.

14. Combination according to claim 13 in which said photosensitive meansis a photoresistor connected in a circuit producing a signal voltagevarying with change in the resistance of said photoresistor andincluding means for driving said servo motor in one direction at a speedincreasing with an increase in said signal voltage when said voltageexceeds a predetermined null value, and in the opposite direction at aspeed increasing with a decrease in signal voltage when said voltage isbelow said null value and including speed control dampening means forsaid motor.

15. A device for guiding sheet material past a work point comprising awork surface, transporting means for feeding a material over the worksurface past the work point, a presser plate positioned opposed the worksurface for the passage of the sheet material between it and the worksurface, gripping means connected to said presser plate and mounted forat least limited rotary motion about an axis substantially extendingthrough said work point, said gripping means being selectively adaptedfor holding engagement with sheet material during rotary movementthereof without substantially impeding action of said transporting meansand means for imparting rotary movement to said gripping means to varythe course of the sheet material.

16. Device according to claim 15 in which said gripping means comprisesa friction surface at a peripheral portion of said presser plateallowing gripping action by differential friction.

17. Device according to claim 16 in which said presser plate is in theform of a disk having an annular friction ring rotatably mounted aboutits periphery and extending past the plane of its surface.

18. Device according to claim 17 including an edge sensor controllingsaid means for imparting rotary movement to said gripping means.

19. Device according to claim 18 in which said edge sensing meanscomprises an optical edge sensor having photosensitive means forreceiving reflected light signals from a narrow area along the path ofsheet material travel over the work surface and means for rotating saidfriction ring in one direction when the intensity of the reflected lightsignal received by said photosensitive means exceeds a predeterminedvalue and in the opposite direction when the intensity of the receivedreflected light signal is below said value.

20. Device according to claim 19 including a fiver optic cableterminating adjacent said area a portion of the fibers of said cablebeing connected to said photosensitive means, a further portion beingconnected to a light source for illuminating said area.

21. Device according to claim 15 including an edge sensor controllingsaid means for imparting rotary movement to said gripping means, saidedge sensor comprising an optical edge sensor having photosensitivemeans for receiving reflected light signals from a narrow area along thepath of sheet material travel over the work surface and means forcontrolling said means for imparting rotary movement to said grippingmeans for rotation in one direction when the intensity of the reflectedlight signal received by said photosensitive means exceeds apredetermined value and in the opposite direction when the intensity ofthe received reflected light signal is below said value.

22. Device according to claim 21 including a fiber optic cableterminating adjacent said area a portion of the fibers of said cablebeing connected to said photosensitive means, a further portion beingconnected to a light source for illuminating said area.

23. Device according to claim 22 in which said photosensitive means is aphoto resistor connected in a circuit producing a signal voltage varyingwith change in the resistance of said photoresistor said means forimparting rotary movement to said gripping means comprising a servomotor and including means for driving said servo motor in one directionat a speed increasing with an increase in said signal voltage when saidsignal voltage exceeds a predetermined null value and in the oppositedirection at a speed increasing with a decrease in said signal voltagewhen said voltage is below said null value and including speedcontrolled dampening means for said motor.

24. Material feed guide system for use with a sewing machine having athroat plate, a reciprocating needle which intermittently moves towardthe throat plate to pierce the material thereon during the stitchingstrokes of the needle and a synchronized feed dog which intermittentlyadvances the material during the transport strokes of the feed dog, saidmaterial feed guide system comprising rotatable gripping means, supportmeans, mounting said gripping means in opposed relationship with thethroat plate to enable the material to be fed between said grippingmeans and said throat plate, said gripping means being movable towardand away from said throat plate for intermittently engaging the materialin holding contact with the material against the throat plate, actuatingmeans for intermittently actuating said gripping means into said holdingcontact with the material, said actuating means operating insynchronized relationship with the needle and feed dog, and means forimparting rotary movement to said gripping means to turn the materialabout the axis of the needle when said gripping means is in holdingcontact with the material against the throat plate to thereby guide thematerial being sewn.

25. Material feed guide system according to claim 24 wherein the feeddog and needle alternately come in contact with the material foralternately transporting the material, then piercing the material in thestitching stroke, then transporting the material, then again piercingthe material in the stitching stroke, and so forth, said material feedguide system having actuating means which intermittently actuates saidgripping means into holding contact with the material during thestitching strokes to turn the material about the axis of the needlewhile the needle is in piercing engagement with the material.

26. Material feed guide system according to claim 24 for use with awalking needle sewing machine wherein the needle and feed dogsimultaneously come in contact with the material for transporting thematerial during the stitching strokes, said material feed guide systemhaving actuating means which actuates said gripping means between thestitching strokes to turn the material relative to the axis of theneedle while the needle and feed dog are withdrawn from the material.

27. Material feed guide system for automatically stitching along an edgeof material for use with a sewing machine having a throat plate, areciprocating needle which intermittently moves toward the throat plateto pierce the material thereon during the stitching strokes of theneedle and a synchronized feed dog which intermittently advances thematerial during the transport strokes of the feed dog, said materialfeed guide system comprising rotatable gripping means, support means,mounting said gripping means in opposed relationship with the throatplate for allowing the material to be fed between said gripping meansand said throat plate, said gripping means being movable toward and awayfrom said throat plate for intermittently engaging the material inholding engagement with the material in slidable contact with the throatplate, the gripping engagement of said gripping means exerting a greaterfrictional force on the material than does the throat plate, actuatingmeans for intermittently actuating said gripping means into holdingengagement with the material, said actuating means being in synchronizedrelationship with the needle and feed dog, a servo motor connected tosaid gripping means for rotating said gripping means, edge means forsensing the position of the edge of the material relative a nullposition with respect to the axis of the needle, control meansresponsive to said edge sensing means for actuating said servo motor forrotating said gripping means in one direction when the edge of thematerial is displaced in one direction relative to the null position andfor rotating said gripping means in the opposite direction when the edgeof the material is displaced in the opposite direction relative to thenull position to turn the material in sliding contact with the throatplate relative to the axis of the needle for guiding the material .toautomatically stitch along said edge.

28. Material feed guide system for automatically stitching along an edgeof the material as claimed in claim 27 in which said edge sensing meanscontinuously senses the position of the edge of the material relative tothe null position and said control means is responsive to said edgesensing means for actuating said servo motor whenever the edge of thematerial is displaced from the null position for rotating said grippingmeans while said gripping means is intermittently in holding engagementwith the material intermittently to turn the material in sliding contactwith the throat plate relative to the axis of the needle thereby tosteer the material with control means being effectively continuous inoperation while the rotatable gripping means intermittently engages thematerial.

29. Material feed guide system for guiding sheet material past a workpoint comprising a work surface, transporting means feeding the sheetmaterial over the work surface past the work point, rotatable gri pingmeans, support means mounting said gripping means in opposedrelationship with said work surface for the material to be fed betweensaid gripping means and said work surface, said gripping means beingmovable toward and away from said work surface for intermittentlyengaging the material in holding contact, actuating means forintermittently actuating said gripping means into holding contact withthe material, and means for imparting rotary movement to said grippingmeans to turn the material in sliding contact with the work surfaceabout the work point to steer the course of the material past the workpoint.

30. In combination with a sewing machine having a throat plate defininga working area, a needle, means for reciprocating said needle between awork engaging position and a retracked position and a feed dog means forintermittently moving said feed dog from a retracked position, means forsynchronizing the actuation of said needle reciprocating means and saidfeed dog actuating means to feed the work when the needle is in saidretracked position, manipulator means mounted for at least limitedrotary motion about said needle, means intermittently causing saidmanipulator means to engage material being passed over said working areaand being synchronized with means for reciprocating said needle, andmeans for imparting a controlled rotary movement to said manipulatormeans when in engagement with the material to vary the course ofmaterial being passed through the sewing machine, said manipulator meansbeing capable of causing rotation of said material independently of anypivotal fixing of said material at a point and comprising a frictionsurface above said throat plate and cooperating therewith to effect aguidance action by differential friction, means mounting saidmanipulator means for limited axial movement toward and away from saidthroat plate.

31. A sewing machine having a needle, means mounting said needle on saidsewing machine for reciprocation between a work engaging position and aretracted position, a throat plate defining a smooth work surface and awork area for said needle, manipulator means adapted to intermittentlyhold material to be sewn over an area thereof and to control the courseof said material through said sewing machine and being synchronized withthe means for reciprocating said needle, and a surface element, meansrotatably mounting said surface element in mating relationship with saidmanipulator means, said surface element being adapted to pressurelycontact the other side of said material when said manipulator means isexerting its action thereon and to allow rotation of said manipulatormeans and said surface element in unison, said machine including apressure foot encompassed by said manipulator means but independentthereof, said manipulator means comprising a ring with a frictionalundersurface mounted from above on said machine from a support memberand adapted for controlled rotary motion, said surface element being aportion of said work surface.

32. ln combination with a sewing machine having a throat plate defininga working area, a needle, means mounting said needle on said sewingmachine for reciprocation between a work engaging position and aretracked position, and a feed dog synchronized to feed when said needleis in said retracked position, manipulator means mounted for at leastlimited rotary motion about said needle and adapted to engage materialbeing passed over said working area, said manipulator means beingsynchronized with the stitching action of said needle, and means forimparting a controlled rotary movement to said means to vary the courseof material being passed through the sewing machine, said manipulatormeans being capable of causing rotation of said material independentlyof any pivotal fixing of said material at a point and means resilientlybiasing said manipulator means against said throat plate for thegripping of said material and being mounted to be axially forced awayfrom said throat plate intermittently by said feed dog whereby thegripping action of said friction surface is released 33. A sewingmachine having a needle, means mounting said needle on said sewingmachine for reciprocation between a work engaging position and aretracted position, a throat plate defining a smooth work surface and awork area for said needle, manipulator means adapted to intermittentlyhold material to be sewn over an area thereof and to control the courseof said material through said sewing machine and being synchronized withthe means for reciprocating said needle, and a surface element, meansrotatably mounting said surface element in mating relationship with saidmanipulator means, said surface element being adapted to pressurelycontact the other side of said material when said manipulator means isexerting its action thereon and to allow rotation of said manipulatormeans and said surface element in unison, said machine having an opticaledge sensor and control unit for controlling the action of saidmanipulator means and a contrast plate adapted to extend under the edgeof material being passed through said work area, said contrast platebeing mounted on said machine independently of said manipulator meansand being adapted (a) to be rotated from a right to a left work positionand (b) to be inserted under the edge of the upper layer of materialwhen more than one layer of material is being processed.

34. In a device adapted to guide sheet material over a work surfacehaving a work surface including a work point and having transportingmeans for feeding sheet material over the work surface past said workpoint, the improvement comprismg:

manipulator means mounted for at least limited rotary motionsubstantially about an axis extending through said work point, saidmanipulator means being positioned to make guiding contact with saidsheet material during rotary movement thereof without substantiallyimpeding the action of said transporting means, means for imparting apredetermined rotary movement to said manipulator means to guide thecourse of the sheet material past said work point, and a presser plate,means mounting said presser plate opposed to said work surface, saidmanipulator means comprising an annular friction ring and meansconnecting said annular friction ring about its periphery on saidpresser plate for rotation about the axis of said work point.

1. In combination with a sewing machine having a throat plate, areciprocating needle and a synchronized feed dog; a presser platemounted opposed said throat plate for the passing of material to be sewnbetween it and said throat plate, gripping means connected to saidpresser plate and mounted for at least limited rotary motion aboutsubstantially the axis of said needle, means for intermittentlyactuating said gripping means in holding contact with material beingpassed between said presser and throat plate in synchronization withstitching action of said needle, and means for imparting rotary movementto said gripping means to vary the course of material being passedthrough the sewing machine.
 2. Combination according to claim 1 in whichsaid gripping means comprises a friction surface at a peripheral portionof said presser plate, allowing gripping action by differentialfriction, said presser plate being mounted for limited axial movementtoward and away from said throat plate, and in which said means forintermittently actuating said gripping means is means for axially movingsaid presser plate.
 3. Combination according to claim 2 in which saidpresser plate is resiliently biased against said throat plate for thegripping of material passed through the machine by said friction surfaceand is mounted to be axially forced away from said throat plate by saidfeed dog upon its intermittent feed actuation, whereby the grippingaction of said friction surface is released.
 4. Combination according toclaim 3 in which said presser plate is in the form of a disk having anannular friction ring rotatably mounted about its periphery andextending past the plane on its surface, said friction ring comprisingsaid gripping means.
 5. Combination according to claim 4 in which saidmeans for imparting rotary movement to said gripping means comprises aservo motor.
 6. Combination according to claim 5 in which said frictionrings is coaxially connected to a ring gear driven by said servo motor.7. Combination according to claim 6 including edge sensing meanscontrolling said servo motor.
 8. Combination according to claim 7 inwhich said edge sensing means comprises an optical edge sensor havingphotosensitive means for receiving reflected light signals from a narrowarea along the path of material travel through the machine, and meansfor actuating said servo motor for rotation in one direction when theintensity of the reflected light signal received by said photosensitivemeans exceeds a predetermined value and in the opposite direction whenthe intensity of the received reflected light signal is below saidvalue.
 9. Combination according to claim 8 in which said photosensitivemeans is connected for receiving reflected light signals from a narrowarea adjacent the sewing machine needle and includes means forilluminating said area.
 10. Combination according to claim 9, includinga fiber optic cable terminating adjacent said area, a portion of thefibers of said cable leading to said photosensitive means, a furtherportion leading to a light source for illuminating said area. 11.Combination according to claim 10 including a contrast plate connectedto said presser plate and positioned to extend under the edge ofmaterial passing through said area.
 12. Combination according to claim11 in which said area immediately precedes the sewing machine needlealong a path of travel of material through the machine.
 13. Combinationaccording to claim 12 in which said friction ring is a rubber ringallowing gripping action by differential friction.
 14. Combinationaccording to claim 13 in which said photosensitive means is aphotoresistor connected in a circuit producing a signal voltage varyingwith change in the resistance of said photoresistor and including meansfor driving said servo motor in one direction at a speed increasing withan increase in said signal voltage when said voltage exceeds apredetermined null value, and in the opposite direction at a speedincreasing with a decrease in signal voltage when said voltage is belowsaid null value and including speed control dampening means for saidmotor.
 15. A device for guiding sheet material past a work pointcomprising a work surface, transporting means for feeding a materialover the work surface past the work point, a presser plate positionedopposed the work surface for the passage of the sheet material betweenit and the work surface, gripping means connected to said presser plateand mounted for at least limited rotary motion about an axissubstantially extending through said work point, said gripping meansbeing selectively adapted for holding engagement with sheet materialduring rotary movement thereof without substantially impeding action ofsaid transporting means and means for imparting rotary movement to saidgripping means to vary the course of the sheet material.
 16. Deviceaccording to claim 15 in which said gripping means comprises a frictionsurface at a peripheral portion of said presser plate allowing grippingaction by differential friction.
 17. Device according to claim 16 inwhich said presser plate is in the form of a disk having an annularfriction ring rotatably mounted about its periphery and extending pastthe plane of its surface.
 18. Device according to claim 17 including anedge sensor controlling said means for imparting rotary movement to saidgripping means.
 19. Device according to claim 18 in which said edgesensing means comprises an optical edge sensor having photosensitivemeans for receiving reflected light signals from a Narrow area along thepath of sheet material travel over the work surface and means forrotating said friction ring in one direction when the intensity of thereflected light signal received by said photosensitive means exceeds apredetermined value and in the opposite direction when the intensity ofthe received reflected light signal is below said value.
 20. Deviceaccording to claim 19 including a fiver optic cable terminating adjacentsaid area a portion of the fibers of said cable being connected to saidphotosensitive means, a further portion being connected to a lightsource for illuminating said area.
 21. Device according to claim 15including an edge sensor controlling said means for imparting rotarymovement to said gripping means, said edge sensor comprising an opticaledge sensor having photosensitive means for receiving reflected lightsignals from a narrow area along the path of sheet material travel overthe work surface and means for controlling said means for impartingrotary movement to said gripping means for rotation in one directionwhen the intensity of the reflected light signal received by saidphotosensitive means exceeds a predetermined value and in the oppositedirection when the intensity of the received reflected light signal isbelow said value.
 22. Device according to claim 21 including a fiberoptic cable terminating adjacent said area a portion of the fibers ofsaid cable being connected to said photosensitive means, a furtherportion being connected to a light source for illuminating said area.23. Device according to claim 22 in which said photosensitive means is aphoto resistor connected in a circuit producing a signal voltage varyingwith change in the resistance of said photoresistor said means forimparting rotary movement to said gripping means comprising a servomotor and including means for driving said servo motor in one directionat a speed increasing with an increase in said signal voltage when saidsignal voltage exceeds a predetermined null value and in the oppositedirection at a speed increasing with a decrease in said signal voltagewhen said voltage is below said null value and including speedcontrolled dampening means for said motor.
 24. Material feed guidesystem for use with a sewing machine having a throat plate, areciprocating needle which intermittently moves toward the throat plateto pierce the material thereon during the stitching strokes of theneedle and a synchronized feed dog which intermittently advances thematerial during the transport strokes of the feed dog, said materialfeed guide system comprising rotatable gripping means, support means,mounting said gripping means in opposed relationship with the throatplate to enable the material to be fed between said gripping means andsaid throat plate, said gripping means being movable toward and awayfrom said throat plate for intermittently engaging the material inholding contact with the material against the throat plate, actuatingmeans for intermittently actuating said gripping means into said holdingcontact with the material, said actuating means operating insynchronized relationship with the needle and feed dog, and means forimparting rotary movement to said gripping means to turn the materialabout the axis of the needle when said gripping means is in holdingcontact with the material against the throat plate to thereby guide thematerial being sewn.
 25. Material feed guide system according to claim24 wherein the feed dog and needle alternately come in contact with thematerial for alternately transporting the material, then piercing thematerial in the stitching stroke, then transporting the material, thenagain piercing the material in the stitching stroke, and so forth, saidmaterial feed guide system having actuating means which intermittentlyactuates said gripping means into holding contact with the materialduring the stitching strokes to turn the material about the axis of theneedle while the needle is in piercing Engagement with the material. 26.Material feed guide system according to claim 24 for use with a walkingneedle sewing machine wherein the needle and feed dog simultaneouslycome in contact with the material for transporting the material duringthe stitching strokes, said material feed guide system having actuatingmeans which actuates said gripping means between the stitching strokesto turn the material relative to the axis of the needle while the needleand feed dog are withdrawn from the material.
 27. Material feed guidesystem for automatically stitching along an edge of material for usewith a sewing machine having a throat plate, a reciprocating needlewhich intermittently moves toward the throat plate to pierce thematerial thereon during the stitching strokes of the needle and asynchronized feed dog which intermittently advances the material duringthe transport strokes of the feed dog, said material feed guide systemcomprising rotatable gripping means, support means, mounting saidgripping means in opposed relationship with the throat plate forallowing the material to be fed between said gripping means and saidthroat plate, said gripping means being movable toward and away fromsaid throat plate for intermittently engaging the material in holdingengagement with the material in slidable contact with the throat plate,the gripping engagement of said gripping means exerting a greaterfrictional force on the material than does the throat plate, actuatingmeans for intermittently actuating said gripping means into holdingengagement with the material, said actuating means being in synchronizedrelationship with the needle and feed dog, a servo motor connected tosaid gripping means for rotating said gripping means, edge means forsensing the position of the edge of the material relative a nullposition with respect to the axis of the needle, control meansresponsive to said edge sensing means for actuating said servo motor forrotating said gripping means in one direction when the edge of thematerial is displaced in one direction relative to the null position andfor rotating said gripping means in the opposite direction when the edgeof the material is displaced in the opposite direction relative to thenull position to turn the material in sliding contact with the throatplate relative to the axis of the needle for guiding the material toautomatically stitch along said edge.
 28. Material feed guide system forautomatically stitching along an edge of the material as claimed inclaim 27 in which said edge sensing means continuously senses theposition of the edge of the material relative to the null position andsaid control means is responsive to said edge sensing means foractuating said servo motor whenever the edge of the material isdisplaced from the null position for rotating said gripping means whilesaid gripping means is intermittently in holding engagement with thematerial intermittently to turn the material in sliding contact with thethroat plate relative to the axis of the needle thereby to steer thematerial with control means being effectively continuous in operationwhile the rotatable gripping means intermittently engages the material.29. Material feed guide system for guiding sheet material past a workpoint comprising a work surface, transporting means feeding the sheetmaterial over the work surface past the work point, rotatable grippingmeans, support means mounting said gripping means in opposedrelationship with said work surface for the material to be fed betweensaid gripping means and said work surface, said gripping means beingmovable toward and away from said work surface for intermittentlyengaging the material in holding contact, actuating means forintermittently actuating said gripping means into holding contact withthe material, and means for imparting rotary movement to said grippingmeans to turn the material in sliding contact with the work surfaceabout the work point to steer the course of the material Past the workpoint.
 30. In combination with a sewing machine having a throat platedefining a working area, a needle, means for reciprocating said needlebetween a work engaging position and a retracked position and a feed dogmeans for intermittently moving said feed dog from a retracked position,means for synchronizing the actuation of said needle reciprocating meansand said feed dog actuating means to feed the work when the needle is insaid retracked position, manipulator means mounted for at least limitedrotary motion about said needle, means intermittently causing saidmanipulator means to engage material being passed over said working areaand being synchronized with means for reciprocating said needle, andmeans for imparting a controlled rotary movement to said manipulatormeans when in engagement with the material to vary the course ofmaterial being passed through the sewing machine, said manipulator meansbeing capable of causing rotation of said material independently of anypivotal fixing of said material at a point and comprising a frictionsurface above said throat plate and cooperating therewith to effect aguidance action by differential friction, means mounting saidmanipulator means for limited axial movement toward and away from saidthroat plate.
 31. A sewing machine having a needle, means mounting saidneedle on said sewing machine for reciprocation between a work engagingposition and a retracted position, a throat plate defining a smooth worksurface and a work area for said needle, manipulator means adapted tointermittently hold material to be sewn over an area thereof and tocontrol the course of said material through said sewing machine andbeing synchronized with the means for reciprocating said needle, and asurface element, means rotatably mounting said surface element in matingrelationship with said manipulator means, said surface element beingadapted to pressurely contact the other side of said material when saidmanipulator means is exerting its action thereon and to allow rotationof said manipulator means and said surface element in unison, saidmachine including a pressure foot encompassed by said manipulator meansbut independent thereof, said manipulator means comprising a ring with africtional undersurface mounted from above on said machine from asupport member and adapted for controlled rotary motion, said surfaceelement being a portion of said work surface.
 32. In combination with asewing machine having a throat plate defining a working area, a needle,means mounting said needle on said sewing machine for reciprocationbetween a work engaging position and a retracked position, and a feeddog synchronized to feed when said needle is in said retracked position,manipulator means mounted for at least limited rotary motion about saidneedle and adapted to engage material being passed over said workingarea, said manipulator means being synchronized with the stitchingaction of said needle, and means for imparting a controlled rotarymovement to said means to vary the course of material being passedthrough the sewing machine, said manipulator means being capable ofcausing rotation of said material independently of any pivotal fixing ofsaid material at a point and means resiliently biasing said manipulatormeans against said throat plate for the gripping of said material andbeing mounted to be axially forced away from said throat plateintermittently by said feed dog whereby the gripping action of saidfriction surface is released.
 33. A sewing machine having a needle,means mounting said needle on said sewing machine for reciprocationbetween a work engaging position and a retracted position, a throatplate defining a smooth work surface and a work area for said needle,manipulator means adapted to intermittently hold material to be sewnover an area thereof and to control the course of said material throughsaid sewing machine and being synchronized with the means forreciprocating said needle, and a surFace element, means rotatablymounting said surface element in mating relationship with saidmanipulator means, said surface element being adapted to pressurelycontact the other side of said material when said manipulator means isexerting its action thereon and to allow rotation of said manipulatormeans and said surface element in unison, said machine having an opticaledge sensor and control unit for controlling the action of saidmanipulator means and a contrast plate adapted to extend under the edgeof material being passed through said work area, said contrast platebeing mounted on said machine independently of said manipulator meansand being adapted (a) to be rotated from a right to a left work positionand (b) to be inserted under the edge of the upper layer of materialwhen more than one layer of material is being processed.
 34. In a deviceadapted to guide sheet material over a work surface having a worksurface including a work point and having transporting means for feedingsheet material over the work surface past said work point, theimprovement comprising: manipulator means mounted for at least limitedrotary motion substantially about an axis extending through said workpoint, said manipulator means being positioned to make guiding contactwith said sheet material during rotary movement thereof withoutsubstantially impeding the action of said transporting means, means forimparting a predetermined rotary movement to said manipulator means toguide the course of the sheet material past said work point, and apresser plate, means mounting said presser plate opposed to said worksurface, said manipulator means comprising an annular friction ring andmeans connecting said annular friction ring about its periphery on saidpresser plate for rotation about the axis of said work point.